[vlmc-devel] [PATCH] MLTBackend: Add MLT service info in logHandler

[Hugo Beauzée-Luyssen]

On 07/29/2016 05:01 PM, Pawel Golinski wrote:
> ---
>  src/Backend/MLT/MLTBackend.cpp | 26 ++++++++++++++++++++++++--
>  1 file changed, 24 insertions(+), 2 deletions(-)
>
> diff --git a/src/Backend/MLT/MLTBackend.cpp b/src/Backend/MLT/MLTBackend.cpp
> index 3d39930..015de8e 100644
> --- a/src/Backend/MLT/MLTBackend.cpp
> +++ b/src/Backend/MLT/MLTBackend.cpp
> @@ -28,6 +28,7 @@
>  #include <mlt++/MltRepository.h>
>
>  #include <mlt/framework/mlt_log.h>
> +#include <mlt/framework/mlt_service.h>
>
>  #include "MLTFilter.h"
>
> @@ -101,8 +102,22 @@ void
>  MLTBackend::setLogHandler( IBackend::LogHandler logHandler )
>  {
>      staticLogHandler = logHandler;
> -    mlt_log_set_callback( []( void*, int level, const char* format, va_list vl )
> +    mlt_log_set_callback( []( void* ptr, int level, const char* format, va_list vl )
>      {
> +        char* prefix_buffer = nullptr;
> +
> +        Mlt::Properties properties( mlt_service_properties( ( mlt_service )ptr ) );
> +
> +        if ( properties.is_valid() )
> +        {
> +            char *mlt_type = properties.get( "mlt_type" );
> +            char *mlt_service = properties.get( "mlt_service" );
> +            if ( mlt_service )
> +                asprintf( &prefix_buffer, "[%s %s] ", mlt_type, mlt_service );
> +            else
> +                asprintf( &prefix_buffer, "[%s %p] ", mlt_type, ptr );

Those asprintf calls should be avoided:
You can't assume asprintf will be available on the target system, as 
it's a GNU extension (the same is true for vasprintf, but manually 
handling the va_arg probably isn't something you want to do :) )
One could also argue that asprintf can fail and that it's not checked. 
std::string can also fail, but in a much less silent way.

> +        }
> +
>          char* buffer = nullptr;
>
>          auto lvl = IBackend::None;
> @@ -118,7 +133,14 @@ MLTBackend::setLogHandler( IBackend::LogHandler logHandler )
>          if ( vasprintf( &buffer, format, vl ) < 0 )
>              return;
>
> -        staticLogHandler( lvl, buffer );
> +        std::string msg_str;
> +        if ( prefix_buffer )
> +            msg_str += prefix_buffer;
> +        if ( buffer )
> +            msg_str += buffer;
> +
> +        staticLogHandler( lvl, msg_str.c_str() );
> +        free( prefix_buffer );
>          free( buffer );
>      } );
>  }
>